• Buku Performance Products – 1/8 Scale Speed-Tune Clutch

    Buku Performance Products – 1/8 Scale Speed-Tune Clutch

    Looking at the majority of members here at beatyourtruck, we will notice that most of them are bashers (after all this is BEATyourtruck). So, you may be wondering, why in the world should we care about a speed tuning clutch? Only racers need to fine tune their machines down to the details of the clutch; us bashers can be lazy and use whatever springs we got laying around. Wrong! That’s the way I used to think about clutches and you may too, but our thinking needs to change.

    It’s easy to see why a racer might want something like this, but it is just as important to have a properly tuned clutch for us too. After all, as a basher we never have power to waste. I know we can be lazy sometimes and we rather not tear down our engines to change the clutch springs; one it’s difficult, two we don’t know exactly what it’s going to do. But Buku helps us out with their speed-tune clutch. With this clutch we can now change the spring rates on the field in a matter of seconds and actually see the difference it makes.

    Packaging and first impressions:
    Nothing to fancy with the packaging, a bag full of parts and instructions is what you’ll get.

    Within that bag of parts, you will receive:
    * A fully assembled clutch
    * A hex wrench
    * Shims, nut, and a brass bushing (in a nice little bag)
    * Two Buku decals
    * An instruction manual (with pictures)
    * An important “read me” instructions

    What stood out the most for me was the greatly detailed instruction manual. It is a four page manual! A full page is dedicated on installing it to you truck, the initial setting of the clutch, and then repeating what the important “read me” instructions said. The second page is installing the shoes, this can be skipped since they had already done that for you. The last two pages are all about tuning the clutch. They did a really good job describing what you need to do to break in the clutch, what steps to go to from there, and what you should be looking for when tuning.

    Even with a four page manual, I still feel they could have added a bit more to the instructions. I think some tips on removing an old clutch would have come in handy. I had to look online to find a video of someone using a battery terminal puller to remove an old clutch. I will have to say that works really well. Also it would have been nice if they had given me a torque value or something to set the nut to; to me that seems like that would be important.

    Enough about that, time for the clutch. The first thing that was going through my head was, “How does it work? And how do you keep the three shoes separate?” It’s actually pretty simple, instead of having the springs placed in a groove on the nut (the hard part of installing clutch shoes), each spring has its own little area with a small set screw pressing on the spring to adjust the tension. It’s pretty slick.

    To keep the shoes separate, so you know which shoe you’re tuning, on the flywheel they put a dab of paint next to the adjustment screw. Shoe number one had green mark, shoe number two had blue mark, and shoe number three had nothing. This is a great idea, except for one thing. The paint they used wasn’t the best. First off, the green and blue looked too much alike. Secondly, the paint wore off really quick. By the time I got done fiddling with it and was ready to hit the field for some test, I could barely tell them apart. It’s not that big of a deal though, you just have to find a new way to mark them. I found some green and blue oil paints and I just remarked them. A scriber would work really nice too.

    The clutch shoes and the flywheel itself looked really nice. Everything looked like it was machined very nicely, no defects, and it had a nice shine to it. The design of the spring tension set up looks very solid too, I do not expect to have any problems with that in the future.


    The LST2 was the lucky contender for the new clutch. I’ve been having a difficult time tuning this truck ever since I bought it used. I knew the engine was good and I had a suspicion the old clutch was causing its fair share of issues.

    Installing the clutch to the truck did not go as well as I thought it would. It wasn’t entirely the clutches fault though. I discovered that my engine had a homemade engine mount, which kind of made tolerances a little tighter than they should have been. The Buku clutch flywheel is a little bit thicker than the old flywheel, so when I got done shimming to the instructions specifications (I actually needed more shims then they gave me), and when I put the clutch bell back on, there were some misalignment issues with the transmission.

    After some tweaking with the transmission and making a new engine mount, I got everything to line up good. I feel that for most trucks there wouldn’t be any issues at all (and the instructions say it fits most trucks), but since I have the custom parts and the really long clutch bell, that may be why it didn’t fit so well.

    Field Test:
    The first thing the instructions said was to break in the clutch. I thought this was interesting, I never knew a clutch needed breaking in, but they explain why and it makes good sense. The first thing I noticed as soon as I started the truck up was the tune on my engine was way off. The idle and low speed were off since the old clutch was always engaged at idle. So while I was breaking in the clutch I tuned my engine to the proper settings.

    The break in setting for the clutch was set on the conservative side. I could tell the clutch wasn’t engaging until a significant amount of rpms was met. After the break in, I followed the instructions very closely, adjusting just one shoe at a time to what they suggested. It was interesting seeing how the truck reacted to each adjustment. I was really impressed how easy it was to make an adjustment. Just turn off the engine, use the wrench they give you, find the shoe you want, make a small turn of the screw, and then fire her right back up and you are good to go.

    After I made it through the basic tuning, I noticed it would run better but I wasn’t overly impressed with the performance. So I read the instruction for the advance tuning, and it told me I need to listen to the engine really closely to see what kind of adjustments to make. So I did just that, and I made a couple slight adjustments, and that’s when I noticed the big gains and became really impressed.

    The basic tuning adjustment did a really good job setting up the clutch for a decent starting point. When you start doing the advance tuning is when you get the big gains. A slight adjustment to just one shoe made such a difference that it was as if I was adjusting the high speed on the engine. I couldn’t believe how much a difference it made. The engine ran so much smoother. I could clearly hear the engine rpms match the speed of the truck. I never realized how much it didn’t match before. The top end of the truck has gotten so much better too. It was hitting a new rpm range that I never heard before, without even tuning the high speed needle.

    Climbing hills is not a problem anymore, since before it used to sound like it would be screaming but not really going anywhere. I now get better acceleration on a hill than what I did on flat ground with my old setup. I am just floored how much better it runs on this clutch. Without the Buku clutch, if I wanted to show off the power of my truck, I would have to lean it way out. Now I have all the power that the engine can give without leaning it out.

    The wear on the shoes was the same as any aluminum shoe clutch. It was obvious which shoe was the leading shoe (one of the shoes is meant to grab before the rest) due to more wear on it. The instruction talked about this and said every so often you need to switch the leading shoe. The shoes aren’t going to last forever, so replacement shoes will be necessary. Buku does however have a ‘komposite shoe’ upgrade which may be something to look into.


    A properly tuned clutch is not just for racers, it is for everyone! I give this two big thumbs up and a must have for your trucks. There is no point to restricting your engine and getting flustered over an engine that just won’t tune when the fix could be as simple as the clutch. The ability to tune a clutch has never been so easy; it can be done on the field in less than thirty seconds.

    Some videos....
    Old Stock Clutch Performance (video link):
    New BUKU Clutch Performance (video link)

    The 1/8 scale 34 mm flywheel clutch comes at a very reasonable price of just $69. For how much this clutch will improve the performance of your engine, it is worth every penny.

    Buku did a phenomenal job with the design of the clutch and did a great job with the instructions. The slight issue that I ran into on installation is dwarfed by the performance of this clutch, and should not give anyone second thoughts about getting one. On top of that, Buku has a 100% satisfaction guarantee, so if you don’t like it you can return it and get your money back.

    Check out Buku today at http://www.bukupower.com/Clutch.aspx

    Special thanks to Asugs, the author of this review. Well done!
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